1. Field of the Invention
The present invention relates in general to air conditioning systems of a motor vehicle, and more particularly to automotive air conditioning systems of a double function type which has two function cycles, one being a cycle for cooling air by practically using the system as a closed refrigeration system and the other being a cycle for heating air while dehumidifying the same by practically using the system as a heat pump system.
2. Description of the Prior Art
Hitherto, various types of air conditioning systems have been proposed and put into practical use particularly in the field of motor vehicles. Some are of the above-mentioned double function type.
In long body passenger cars, such as one-box type vehicle or the like, there have been also used a so-called duel air conditioning system which comprises a first air conditioning unit for conditioning air in a relatively front part of a passenger room and a second air conditioning unit for conditioning air in a relatively rear part of the passenger room.
Nowadays, for obtaining advantages of the double function type, some of the dual air conditioning systems employ the principal of the double function type. That is, for example, the first air conditioning unit comprises an evaporator constituting part of an air conditioning system of double function type and a heater core fed with engine cooling water, and the second air conditioning unit comprises another evaporator connected to the air conditioning system and a condenser connected in series with the evaporator to serve as a heater.
However, due to inherent construction, the air conditioning systems of the above-mentioned dual type have failed to give users satisfaction. That is, the second air conditioning unit of the systems has failed to provide the rear part of the passenger room with a satisfactorily warmed air particularly in cold seasons.
It is therefore an object of the present invention to provide an automotive air conditioning system of double function type, which is free of the above-mentioned drawback.
It is another object of the present invention to provide an improved automotive dual air conditioning system which incorporates thereinto the principle of the double function type.
It is still another object of the present invention to provide an improved air conditioning system of double function type for an electric vehicle.
According to a first aspect of the present invention, there is provided an air conditioning system for a vehicle, which comprises a first cycle including a compressor, a first condenser, a second condenser, a liquid tank, an expansion valve and an evaporator which are connected through pipes to form a first refrigerant circulation circuit through which a refrigerant flows from an outlet of the compressor to an inlet of the compressor while changing the phase, the first cycle causing the evaporator to act as a cooler when operated; a second cycle including the compressor, the second condenser, the liquid tank, the evaporator and the evaporator which are connected through pipes to form a second refrigerant circulation circuit through which the refrigerant flows from the outlet of the compressor to the inlet of the compressor while changing the phase, the second cycle causing the condenser to act as a heater and the evaporator to act as a cooler when operated; switch means for switching the first and second cycles; an air duct case having an air flow passage in which the second condenser and the evaporator are installed, the air flow passage being connected at its downstream part to a passenger room of the vehicle; and heater means for heating a returning refrigerant which, under operation of the second cycle, flows in the pipe extending from an outlet of the evaporator to the inlet of the compressor.
According to a second aspect of the present invention, there is provided a dual air conditioning system for a motor vehicle powered by an internal combustion engine. The dual air conditioning system comprises a first system including a first cycle, a second cycle and first switch means for switching the first and second cycles, the first cycle including a compressor driven by the engine, a first condenser, a first liquid tank, a first expansion valve and a first heat exchanger which are connected through pipes to form a first refrigeration circulation circuit through which a refrigerant flows from an outlet of the compressor to an inlet of the compressor while changing the phase, the second cycle including the compressor, the liquid tank, a second condenser, a second liquid tank, a second expansion valve and a second heat exchanger which are connected through pipes to form a second refrigeration circulation circuit through which the refrigerant flows from the outlet of the compressor to the inlet of the compressor while changing the phase, the first system causing the first and second heat exchangers as coolers when operated; a second system including a third cycle which includes the same parts as those of the first cycle except the first condenser, a fourth cycle which includes the same parts as those of the second cycle except the first condenser and a second switch means for switching the third and fourth cycles, the second system causing the first and second heat exchangers as coolers and the second condenser as a heater; a heater core to which a warmed water is led from a water jacket of the internal combustion engine; an air duct case having a first air flow passage in which the heater core and the first heat exchanger are installed, and a second air flow passage in which the second condenser and the second heat exchanger are installed, each of the first and second flow passages being connected to at downstream part to a passenger room of the vehicle; and heater means for heating a returning refrigerant which, under operation of the second system, is about to enter the inlet of said compressor.
According to a third aspect of the present invention, there is provided a dual air conditioning system for a motor vehicle powered by an internal combustion engine. The system comprises a first cycle including a compressor driven by the engine, a first condenser, a first liquid tank, a first expansion valve and a first heat exchanger which are connected through pipes to form a first refrigerant circulation circuit through which a refrigerant flows from an outlet of the compressor to an inlet of the compressor, the first cycle causing the first heat exchanger to serve as a cooler when operated; a second cycle including the compressor, a second condenser, a second liquid tank and a second expansion valve which are connected through pipes to form a second refrigerant circulation circuit through which the refrigerant flows from the outlet of the compressor to the inlet of the compressor, the second cycle causing the second condenser to serve as a heater when operated; switch means for switching the first and second cycles; a heater core to which a warmed water is led form a water jacket of the internal combustion engine; an air duct having a first air flow passage in which the heater core and the first heat exchanger are installed, and a second air flow passage in which the second condenser is installed, each of the first and second air flow passages being connected at a downstream part thereof to a passenger room of the vehicle; and heater means for heating a returning refrigerant which, under operation of the second cycle, is about to enter the inlet of the compressor.
According to a fourth aspect of the present invention, there is provided an air conditioning system for an electric motor vehicle. The system comprises a first cycle including a compressor driven by an electric motor, a first condenser, a second condenser, a liquid tank, an expansion valve and an evaporator which are connected through pipes to form a first refrigerant circulation circuit through which a refrigerant flows from an outlet of the compressor to an inlet of the compressor while changing the phase, the first cycle causing the evaporator to serve as a cooler when operated; a second cycle including the compressor, the second heat exchanger, the liquid tank, the expansion valve and the evaporator which are connected through pipes to form a second refrigerant circulation circuit through which the refrigerant flows from the outlet of the compressor to the inlet of the compressor while changing the phase, the second cycle causing the condenser to serve as a heater and the evaporator as a cooler when operated; switch means for switching the first and second cycles; an air duct case having an air flow passage in which the second condenser and the evaporator are installed, the air flow passage being connected at its downstream part to a passenger room of the electric vehicle; and heater means for heating a returning refrigerant which, under operation of the second cycle, flows in the pipe extending from an outlet of the evaporator to the inlet of the compressor.